Improvement in modes of manufacturing piston-springs



J. MITCHELL.

MODE OF MANUFACTURING PISTON-SPRINGS.

1 No. 171,157. Patented Dec. 14,1875.

UNITED STATES PATENT OTF on JOHN MITCHELL, OF PHILADELPHIA,PENNSYLVANIA.

IMPROVEMENT IN MODES OF MANUFACTURING PISTON-SPRINGS.

Specification forming part of Letters Patent No. 171, [57, datedDecember 14, 1875; application filed 7 November 22, 1875.

To all whom it may concern:

Be it known that 1, JoHN M1ToH LL, of Philadelphia, Pennsylvania, haveinvented an Improved Mode of Manufacturing Piston- Springs, of which thefollowing is a specification l The object of my invention is to make amore durable and efficient sprin for forcing out the packing-rin gs ofpistons than those of ordinary construction; and this object I attain inthe manner which I will now proceed to describe, reference being bad tothe accompanying drawing, in which Fig. 1 is a view of a steel bar,formed for conversion into the piston-spring, and Fig. 2 the bar coiledto form the spring.

In manufacturing springs of this class it has been the practiceheretofore to turn a castiron cylinder inside and out, and then to severit spirally, so as to form the desired spring, which is of limitedresiliency and wanting in durability, owing to the removal of the skinof the metal by turning. l

I discard cast-iron as a metal for the manufacture of these springs,which I make of steel I I take a flat, steel bar, at about the line asm, I weld the end of a bar, I), of steel of the same length as the bara, and of the tapering'torm shown in Fig. 1.

The bar thus formed is without any preparation of its surface other thansimple cleaning coiled to the desired form of a piston-s 'iring, whichis stronger in proportion to its Weight, and much more durable andelastic than an ordinary cast'iron spring. I prefer to form the taperedbars I) b by first taking a plate, 0, Fig. 3, and then severing it onthe dotted line y by a planing-machine or other suitable means, so as toform two bars having the required taper. Other means of forming thesebars may, however, be employed.

I claim as my invention- The mode herein described of manufacturingpiston-springs-that is to say, first, forging a bar of'steel to theshape, Fig. 1, and then coiling the bar, as set forth.

In testimony whereof I have signed my name to this specification'in thepresence of two subscribing witnesses.

JOHN MITCHELL. Witnesses:

' HARRY HoWsoN, Jr.,

HARRY SMITH.

